1. Field of the Invention
The present invention is directed to a short, light-weight jet engine nozzle that will operate efficiently over the complete operating Mach number range of a supersonic aircraft or missile. More particularly, the present invention is directed to an engine which is provided with an arrangement for varying the area of the nozzle thereof for altering the exhaust characteristics of the engine nozzle structure in accordance with operation of an aircraft or missile within the subsonic and supersonic ranges.
2. Description of the Prior Art
An exemplary prior art engine-nozzle combinations is illustrated in FIG. 1 of the present application which shows a 1975 technology turbojet engine 8 and nozzle 9 combination. The nozzle 9 has many movable parts, among which are movable tail feathers 1, inner door flaps 2, outer door flaps 3, secondary air valves 4, and a noise suppressor 5. Movement of these elements allows the nozzle to operate efficiently at both supersonic and subsonic speeds with relatively low noise levels at takeoff and approach speeds. However, engine-nozzle combinations as shown in FIG. 1 suffer from a number of disadvantages including their long length and also the heavy weight of the nozzle. Furthermore, if sound suppression is required at takeoff and approach speeds, the weight and complexity of the suppressor 5 is also a disadvantage.
Other examples of the prior art include U.S. Pat. Nos. 3,005,308, 3,897,001 and 3,642,209. All of the inventions in these patents have, in common with the present invention, translating nozzle parts to vary the nozzle exit area. U.S. Pat. No. 3,005,308, issued to Bader, shows a nozzle with alternate translating segments that vary the area of a conventional convergent-divergent nozzle. The variable area nozzle arrangement of the Bader patent can best be seen in FIG. 3 which shows a plurality of vane segments 26 to 34, said vane segments being divided into two sets which include alternate members thereof. A first set of such segments include members 27, 29, 31 and 33, which are fixed, whereas a second set of segments which include segment members 26, 28, 30, 32 and 34 is axially, translatably movable with respect to the fixed segments. However, the nozzle disclosed in the Bader patent is much longer than that of the present invention, and thus does not achieve the shortness in length and light weight of the engine of the present invention. Also, increasing the number of translating segments does not change the overall length of the engine of the Bader patent. In addition, when the segments are translated from their "all-together" position, the nozzle is no longer smooth, but has many sharp corners and steps which lead to poor aerodynamic performance.
U.S. Pat. No. 3,897,001, issued to Helmintoller, Jr., et al, merely pertains to an inlet engine nozzle system wherein the nozzles shown therein are of the well-known plug nozzle type. The plug translates to vary the exit nozzle and is, of course, much longer than the nozzle of the present invention and accordingly, is much heavier than the nozzle of the present invention.
U.S. Pat. No. 3,642,209, issued to Stahl, shows a nozzle configuration which has little in common with the present invention since the outer sleeves thereof translate to vary the exit area. In addition, the nozzle, as shown, is only a convergent nozzle wherein the exit area is the minimum area, and thus is suitable for only subsonic and low supersonic applications.